Comments

-5:1 modulation for the Vitodens: I simply assumed that factor, because that's the factor that one usually observes with the mod/con boilers. And only IBC (so I heard) would be capabale of higher ratios?

-Other local boiler manufacturers/suppliers: besides Viessmann and Lochinvar, I'm not aware of others. There are Triangle Tube Prestige models sold via globalindustrial.ca, and Rinnai boilers sold via ... amazon.ca. This is a hint that there may be some local suppliers available for those. Any personal opinion on Rinnai ones? (I already have a tankless/instant water heater from Rinnai). Having access to replacement parts and tech service reps is a good point.

67 divided by 31 is about 2. Hence the modulation ratio is about 2 to 1. Another example: the WHN055 is 55 divided by 11. That corresponds to 5 to 1. The IBC is 150 divided by 15, so it is 10 to 1. But the significant number here is really the minimum btu output. If your project's requirements are always below the minimum, than the boiler will almost never have the opportunity to modulate. If that is the case, than why buy a modulating boiler? This is why I think it is really worth your time to search out other equipment that can hit lower minimum btu outputs. 10,000 is about the lowest I am aware of, but it wouldn't surprise me if there are smaller models.

Regarding pumps: It sounds like you pay about 14 cents per kwh. Most of the electrical savings results from eliminating unnecessary pumps. A modern ecm pump would likely use less than 30 dollars a month even if it ran every minute of the day continuously. I think the savings associated with variable speed technology may shave a little off that amount during the shoulder seasons, but even when throttled down, traditional variable speed pumps fair quite poor. In light of this, it's not really a big deal weather or not you are allowed to use a variable speed pump in a directly pumped configuration. (at least in terms of electrical savings)

You spoke with Lochinvar? What was their concern with variable speed?

Regarding the Rinnia: I have no opinion on the Rinnia, Loch, Vitodens, or anything else. I'm not a boiler guy --I'm more interested in the thermodynamics and the practical engineering compromises that manifest in projects that are typical on these forums. Having said that, I find the claimed advantages with the vertical firetube heat exchangers at least credible, and there have been real world positive reports posted on this website. The disadvantage is the extra water in the hx associated with the design. During the summer, domestic hot water production leaves behind unused energy after each firing cycle. This can be improved with post purge cycle but the loss is never completely eliminated. However, in a predominately cold climate, I would expect such a disadvantage to be outweighed by lower pumping requirements and possibly an improved maintenance schedule.

Another thing for you to contemplate: Many boilers can except control signals from more sophisticated ODR + indoor feedback controllers. Check out Tekmar --I believe they are Canadian. Another player is the the Honeywell Aquatrol system, but I find their documentation lacking. There are others too, but these are probably the most readily available and accessible. These controllers have some very impressive features, but it is hard to justify the extra cost for a small project.

-Viessmann WB2B-19 mod factor: yes, it looks like 2:1 and was puzzled about it, as usually the mod boiler manufacturers strive for 3:1 or 4:1.

-Yeah, good point about the min BTU output. 31K it's almost at my upper heat loss/need range. So, it's not only the higher hydraulic resistance, but also this factor - making the Viessmann less ideal for my need. 10K on the other hand is great - about each of the 3 floors of the house can make such demand. And the WHN055 will also be in very low modulation range almost all the time, thus featuring a higher efficiency (this eff usually goes lower when you reach the max BTU output).

-Lochinvar: I have asked that question to the local engineer/sales representative. Waiting for an answer.

-Firetube design: it's a non-issue for me that it's at slight disadvantage for the DHW production purposes. As I won't use it for that. Thanks for confirming that somehow the feedbacks from the field are showing such design as passing with high marks.

-Lochinvar Knight reliability: I've heard that the wall hung models of Knight are a bit harder to do maintenance with, comparing to the floor standing models - hard for the technician to reach the parts. I am also concerned a bit about the fact that the electronics board (both high voltage and low voltage) are placed near the boiler cylinder itself, in the same compartment? And the concentric venting is not by default with Lochinvar and you have to use a "Y" type of connector, which practically needs more space/longer routes for a side wall venting?

-In terms of var speed vs fixed pump, I understand that in a "fixed non-ECM" pump vs "variable non-ECM" pump scenario, the latter won't bring significant power savings. Because the var non-ECM pumps are not highly efficient due to their electric design (triacs and no permanent magnets?). What about a fixed ECM pump (i.e. Grundfos Alpha 15-155 set to fixed mode) vs a var speed non-ECM pump? The fixed ECM one would still be better, right?

I think the only considerable advantage that a var speed non-ECM pump (i.e. one controlled by a 0..10VDC input signal) is not the power savings, but rather the fact that it helps the boiler to achieve the intended Delta-T (a feature which we would love to have with Viessmanns here - as Europe already has it) ? In other words, the boiler will be in more control, and adapt the external devices to its need, not the vice-versa.

Also, in a P/S circuit, it would be interesting what the benefit will be in Lochinvar's case, with the primary pump being variable (non-ECM) and driven by the boiler, and with the secondary pump a Delta-P pump which would come also with an output 0..10VDC interface - and its output would be read back by the boiler (the WHN055 has also a 0..10VDC input). But I wouldn't go with a P/S configuration just for the sake of having this dual signal interfacing, right ? :-)

So, which of the 4 following scenarios do you think would be the best with WHN055:

(2) still one pump/one circuit, but with a var speed Grundfos 0..10V DC var speed pump with the input driven by Lochinvar. (pump coming as standard with the boiler would be discarded/put away).

(3) still one pump/one circuit but with a Grunfoss Alpha 15-55 ECM pump, set to fixed speed.

(4) P/S circuit, with primary circuit having the var speed pump from case (2) and secondary circuit the Alpha pump from case (3), and unfortunately the North-American model of Alpha not being able to provide a 0..10VDC output signal back into Lochinvar.

-In terms of control features, I would be ok with the basic ODR functionality. As long as it allows you to select various curves. Btw, Lochinvar seems to show linear cuves (you just select those 4 parameters - outdoor low and high limit, and indoor low and high limits). You don't see those various non-linear pre-defined curve (coded by a numbers) as in Viessmann. Also, I'm happy that I can reuse my existing thermostat (and I could invest in a better one much later, i.e like this one made by Trane in cooperation with Honeywell:

But my concern about indoor feedback is: can I get something similar to the Vitotrol - something to communicate the real indoor temp back to the boiler, instead of just an on/off signal? Or, as long as I'll be using the on/off thermostat only as high temp limiter and define any (slight) setbacks only at the boiler control level and not the thermostat, I'll be fine?

Stupid question: when looking at a boiler manufacturer's specs, how can one figure out the min required flow rates?

For both Viessmann WB2B-19 and Lochinvar Knight WHN055, I was able to see the max (or typical) flow rates. As Chris had mentioned earlier in this thread, the WB2B-19 has 6.1 gpm. Also the Knight shows 5gpm. At a Delta-T of 20F, that is.

How do you infer the min. value? By looking at the typical value that is stated for the max. Delta-T which the boiler's controls can support? (i.e. 40F Rise 3.1gpm for Viessmann and 35F rise 3.0gpm for Knight?)

If that's the case, then when attempting to use the WHN055, for a heat load of 33kBTU, I would require 3-3.3gpm for Delta-T=20. Wouldn't that flow rate be too close to the min rate, and thus making the use of a direct connection (i.e. no P/S) dangerous?

and boy, so much info to absorb. Chris had made a very interesting point about the usefulness of a LLH/P-S separation, from a different "angle" - that being to aim for higher delta-T in the boiler circ to increase condensation (lower return temps). And which would trigger low gpm and small pump sizing in boiler circ.

But on the other hand, you too made a very interesting point - how come a P/S circuit with dT = 40 in primary (180/140) is more efficient than a non-P/S circuit with dT=20 (160/140 supply/return temps)?

I intuitively feel that the best scenario for my case is still one circuit, and using only one pump, but "standard size" and ECM. With these 3 scenarios for that ECM pump:

(1) With a variable input interface, OR

(2) that ECM pump to provide an output interface back into the WHN055.

(3) Or a third case - a simpler ECM pump (bumblebee or Stratos or Alpha) and neither providing output nor input to/from the WHN electronic board (via that 0...10V DC).

The case #3 is easy. But how can we be sure that it won't get too low flow and panick the boiler? I guess you have to guarantee at least 9-11 kBTU all the time for that to happen?

Case #1 can be done with Wilo stratos - a special adapter can be purchased to provide analog 0...10VDC input into the pump. Grundfos alpha doesn't have such adapter - only the Magna has it and that's too big, plus the Magna works at 230V only.

Case #2 is hard to implement - couldn't find such interface (pumps providing an output signal that WHN is ready to read).

Also, in this var speed (boiler) pump mode, we know from the WHN manual that the boiler will attempt to implement a const Delta-T alg. But the params of this alg can't be found in the boiler's menus, so I guess it's not flexible (i.e. to tell it the nature of the emitters etc)...But at least the alg exists, and that's good.

I too wonder about minimum flow at minimum modulation in the context of variable speed pumping and suggest starting a new thread specifically on this topic to get some feedback from a broad range of installers. I would imagine that some designs may be susceptible to bubble accumulation at extremely low flows and the ultimate answer may vary from model to model. There may be issues with laminar flow film boiling, too. High deltas at modulation minimums isn't a very common condition and I'm not convinced this is acceptable.

You found the Wilo ecm pump that can take a control signal --does it require 230 volts? I hesitate to recommend a specific pumping strategy in a well balanced system without hydraulic separation. I really don't think there is a tremendous amount to be gained with the more sophisticated approaches in this circumstance, although personally I'd enjoy the experimentation. The 0-10v alpha output mentioned does not quite sound right in particular. I believe the 0-10v input on the boiler controls only the flame modulation. This would leave you with a system that only modulates on flow with no direct control over the water temperature. Does the manual discuss this arrangement in particular? Perhaps there are other settings that can be activated that I am not aware of. I can see where this would be useful but I don't know that I would want it to take the place of ODR temperature control. I'm also concerned, regardless of whether it has 0-10v output or not, that a delta P pump may be capable of modulating flow much faster than the burner response. I foresee circumstances related to zone flow changes in which a delta P would aggravate spikes in the delta T across the boiler.

A fixed speed or deltaT boiler controlled pump would be more likely to mitigate such problems, but perhaps it's really a non-issue and I'm just being over cautious.

Also, keep in mind that there is nothing preventing one from putting pumps in

parallel and series. The resulting pump curves may allow for small

piping that is quite useful in retrofit circumstances.

Regarding "something to communicate the real indoor temp back to the boiler." I wouldn't be too quick to give up on this feature. These systems use their own thermostats that report back to the controller. The controller takes in all the indoor and outdoor temperatures, the occupant requested temperatures, and computes a water temperature that is adjusted throughout the day, automatically correcting temperature errors as loads change. The boiler does not receive this information, it merely is modulated via 0-10volt to achieve the requested water temperature. (The controller has a water sensor and may even control the primary pump directly in addition to any downstream mix systems for multiple parallel indoor feed backs.) The Tekmar system in particular can even control staged or ratio based parrellel deliver of heat into the same zone if, for example, you had a slow response heated floor, medium response time radiators for stage 2, and rapid temperature control forced air for stage 3 all in the same room! I think the Honeywell system is more cost effective though.

For a WB2B19 is 1.6gpm on a 35 Temp Rise. Boiler btu/hr output on low fire is 28K

Low Fire 28,000 /(35x500) = 1.6gpm

High Fire 61,000 / (35 x 500) = 3.5gpm

Just change the temp rise in the equation for a 20, 25 or 30. So if your boiler pump can modulate from 1.6 to 3.5 to match the boilers btu/hr out put at any given time in the system then it's a home run. Your right, like they do across the pond.

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

I have attached 2 PDFs detailing which IF modules are available. Now, as SWEI was hinting, it may be that we are out of luck with the ECO model in particular :-(

The Wilo_Pump_Control_Management.pdf doc seems to list only these types of modules for the ECO MHIE model (whatever MHIE means?): Modbus, BacNet, CAN, LON, PLR. I don't know what CAN and PLR mean. Maybe some protocols?

The 26-Stratos_Interface_Module_0803.pdf doc shows on page 2 (section 3.2 - Function), that only the following IF modules support 0-10V inputs: "Ext Off", "Ext Min" and "SBM". Page 3 Fig. 4.2, 4.3 and 4.4 show the terminals.

Now I'm not sure anymore that ECO can accept such interface, and even if it can, I guess it will be hard to find one?

-Regarding the WHN055 0-10V input signal, to be clear, there are 2 0-10V inputs. One is labeled "BMS IN" and it's used by an external "Building Management System" and we aren't referring to that one.

"Variable speed system pump: If a variable speed pump is used in the primary loop, and a 0-10V signal is available from the pump speed control, this signal can be used by the SMART SYSTEM control to anticipate changes in the building heat load. By connecting this 0 - 10V signal to the 0 - 10V SYS PUMP IN terminals, the boiler (or cascade) can modulate up and down as the primary flow increases and decreases."

Now, it's a bit unclear what modulation as term refers to in general. Modulation only for the fire, or other things. But, even if it were for the fire (as you said), wouldn't that corelate to proportional water temps as well? Otherwise, wouldn't that input be identical to the "BMS IN", or Plug 144 from Viessmann Vitotronic 200 ("external 0-10V signal" for dictating boiler modulation)?

First of all I don't get it - why it speaks about a primary loop?? Initially I thought it's a typo. But it insists and repeats the same term at the end of that section. Maybe it's referring to a multi-boiler / LLH setup, where the primary loop as concept is extended to be the loop to which all the cascaded boilers are connecting?

Or maybe that signal input cannot be synthesized by any existing pump (no matter how smart and/or ECM it is) - but IN FACT that's a more complex signal, which the BMS/external management system is generating (variable frequency driver)??

It's too bad that Lochinvar does not give examples of such pumps (featuring outputs instead of inputs). The only thing exemplified in the manual is the var speed (aka variable voltage) pump. They give 2 examples: Grundfos UPS 26-96FC/VS and Taco TACO 0013 IFC VS.

The other doc, service manual ([u][color=#0000ff]http://lochinvar.com/_linefiles/WH-SER%20Rev%20G.pdf[/color][/u]) mentions absolutely nothing about any configurations or more explanations about this input. It's saying only about the BAS 0-10V input signal a lot of things. And about the 0-10V variable output for driving a var speed pump in const Delta-T mode (see Page 26: "Boiler Pump Minimum Voltage: The speed of the boiler pump can be controlled by the SMART SYSTEM control in order to maintain a minimum dT through the heat exchanger. Thus, as the firing rate decreases, the speed of the boiler pump can decrease as well. The SMART SYSTEM control outputs a 0 - 10V signal to the boiler pump to control its speed. The Boiler Pump Minimum Voltage parameter determines the minimum voltage given to the boiler pump, thereby setting its minimum speed. The range of this setting is 2.5V to 10V. The default setting is 3.5V."

Btw, the service manual is quite interesting, because it mentions that the BAS 0..10V input plug can be configured in two ways: to mean a firing rate (a Power percentage) or a setpoint value (see same Page 26, section "BMS Type"). It is a hint that you may be able to connect there not a true, full-fledged BMS, but a smarter thermostat, which would be able to shift the ODR heat curve up and down, that is, something similar to Vitotrol 300?

-"I don't know that I would want it to take the place of ODR temperature control."

It's still unclear if "SYS PUMP IN" is like an "external demand for modulation" (as the BAS in terminal seems to do or Viessmann #145). Maybe the ODR-driven control is still not bypassed?

-"A fixed speed or deltaT boiler controlled pump would be more likely to mitigate such [...flow spikes from Delta-P pumps...] problems, but perhaps it's really a non-issue and I'm just being over cautious."

Interesting, so at least we know that by using a var speed pump (ECM or not, but ECM would still be preferable) connected to the 0..10VDC boiler output, it will be beneficial, acting like a const Delta-T pump. Now the question is: would the Lochinvar's internal control be more flexible/capable than a Taco VFD pump (non-ECM) or even than a Bumblebee? In the sense that it not only counts on the internally attached "inlet boiler temp" and "system supply" temp sensors, but it may know other things, which a Taco Delta-T pump cannot know?

The other question about variable voltage-driven pumps that are non-ECM: aren't they more prone to failures and rotor vibrations at low speeds? Making them noisy and shorter lifetime? That's the reason for seeking an ECM.

Maybe I could use a Magna if I can make 230V in my house? For that one an interface input module can be found for sure. But wouldn't that pump be too big for the job? :-)

-"Also, keep in mind that there is nothing preventing one from putting pumps in

parallel and series. The resulting pump curves may allow for small

piping that is quite useful in retrofit circumstances." Could you please elaborate on that? Are you thinking about scenarios where standard pumps cannot accommodate the head/flow and more power would be needed?

-"Regarding 'something to communicate the real indoor temp back to the boiler.' I wouldn't be too quick to give up on this feature. [...] The boiler does not receive this information, it merely is modulated via 0-10volt to achieve the requested water temperature."

You are so right about this. I was evaluating some Tekmar controls. Listed here:

...and while studying them, I came to this revelation: they are great, but many of their functions are just overlapping with what the Knight WHN055 already know!

Things like the ODR and water inlet, supply and system supply sensors. Heck, the WHN055 has even a built in gas flue sensor. So basically, I would have to pay too much for an external control, and some built-in feature from the boiler will stay unused (money thrown away?). Honestly, the only feature from WHN055 that I feel like missing is this: continuous indoor temp feedback sent to the boiler (as opposed to on/off).

You know something? NOW I'm starting to understand what Mr. greeny had said by "If you install a Vitodens 200 its the cheapest communicating t-stat on the market!" So basically, while trying to find a solution of a more advanced, continuous "indoor feedback" for Lochinvar, I suddenly realized that Vitotrol is something great and a pity to not have it :-) Eastman, do you know what would be the simplest Tekmar control which could be interfaced into the BMS 0..10V input terminal and able to only provide indoor feedback and leave the built-in ODR control of the WHN055 in place? Or I'm asking the impossible?

Ah, I think you are right. The ECO is being considered the "dumbed down" version of their Stratos line. Please take a look at those 2 PDFs that I attached in the next message - perhaps you could infer more info than myself on their possibilities?

SWEI, you were suggesting in another thread the use of the Bell & Gossett's EcoCirc e3 pump? Is such thing generally available on the US market?

I'm basically looking for a way to combine the best of two worlds: the fact that WHN055 can modulate a var speed pump (i.e. through something like a Taco Viridian or variable voltage pump) with the more efficient ECM techology. And can't find a solution yet.

Aha, cool! So in fact the boiler does not know about flow rates, nor it's having any special flow detector/counter. And the magic thing that it knows seems to be the max Delta-T allowed?

So basically, the min flow can be calculated for any boiler using this formula (UHF-driven)?

minFlow = min_fire_btu / (500 x max_delta_t_allowed) ?

[btw, it's interesting that Viessmann is specifying the min BTU output according to DOE. Lochinvar specifies only the max outuput, and expressed in AHRI ratings. I don't know the difference - is that I=B=R type of rating?]

In our WHN055 case, it would be 11,000 / (500 x 35) = 0.628 gpm ? It's nice if it can sustain such low requirement.

I guess one third of the house (one floor) could sustain that for sure. Considering that the main floor will have 6 double-convector rads plus one bathroom towel rad. Aall rads being calculated for 130F/110F operating temp and 76F room temp i.e. 24 celsius and something. The total heat loss for the main floor is 12,429 BTU and I have sized the rad including a 20% additional margin of safety. So basically, at 130/100F (dT = 20), the total flow for that one floor will be 12,429 * 1.2 / (500 x 20) = 1.5 gpm.

The other question is: how one can figure out the max Delta-T rise that a particular boiler supports? SWEI was mentioning about a "boiler ∆T alarm level" - where can that be found?

It would be interesting also to know what pump driving scenario would be more optimal in my particular case: a varspeed pump driven by WHN directly via 0...10V out signal, or an Alpha/Stratos/Bumblebee pump (still connected to the boiler relay because let's say we are willing to trade off the Grundfos "adapt/learn" feature for the ability to have the pump powered on and off by the boiler's relay).

And finally: could we dare to use TRVs (e-TRVs like Danfoss Living ECO) in such direct pipe setup - where also a varspeed pump is driving the show?

Assuming that the whole mainfloor (which will have the termostat anyway) will not have any e-TRV. Out of 14 total rads, only 5 will have eTRV: 3 bedrooms (3 rads) on the upper floor, and 2 rads in basement. 9 rads (including the 3 towel rads which are for all bathrooms) will not have TRVs.

Flow rates are in every manual. I would call Loch and find out from them the min flow rate they want across the HX. I know what Viessmann allows and there reasoning for it.

Do you not have to use the Loch Supply sensor when utilizing the variable pump feature. I believe the boiler is going to vary the speed of the boiler pump off the need of the system supply temp. When piped pri/sec it accounts for the down stream mix. As the boiler delta shrinks it will head to low fire, change the pump flow rate until it sees the down stream temp need diminishing then speed back up as the boilers delta increases and supply out decreases always trying to keep from going off on high limit until the zone is satisfied.

Thus the need of the primary flow rate not having to match the system flow rate.

I had a nice conversation today from someone I know that had a hand in designing the Weil Ultra control. That boiler will not lock out until it sees a 59 degree delta. Found that interesting. Just goes to show how much you can play around with mod/cons. I pretty much know there is a lot of conservative thinking given in the manuals.

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

No idea, the manual is super confusing on this. If I had to guess, I would say it functioned in the same manner as the BMS input, but as you've noted there doesn't seem to be any parameters associated with it. Call a rep and find out for us --I highly doubt it does anything complex but who knows?

"Btw, the service manual is quite interesting, because it mentions that

the BAS 0..10V input plug can be configured in two ways: to mean a

firing rate (a Power percentage) or a setpoint value (see same Page 26,

section "BMS Type"). It is a hint that you may be able to connect there

not a true, full-fledged BMS, but a smarter thermostat, which would be

able to shift the ODR heat curve up and down, that is, something similar

to Vitotrol 300?"

It wouldn't shift the ODR curve. The BMS input overrides the system. The 0-10volt either controls flame %, or setpoint temp. The on board ODR logic is not part of the loop. This is why a 3rd party boiler controller must have its own ODR logic.

"I believe the boiler is going to vary the speed of the boiler pump off

the need of the system supply temp. When piped pri/sec it accounts for

the down stream mix."

My interpretation was that the variable boiler pump output signal is really just locked to the modulation rate. So one would still have to select an appropriately sized pump for the desired delta. The assumption being that if modulation gets cut in half, and pump output gets cut in half, than the delta must remain about the same. I really don't think there is a feedback loop to an actual measured temperature delta except indirectly via the normal target temp control.

we can't know that the output signal driving the var speed pump is tied to the modulation/firing rate. Maybe both the firing rate and that var speed pump signal are driven by an upstream logic/controller.

sounds good, thanks for explaining it and recommending the installation of that sys supply sensor (which makes sense even in a direct loop scenario - because Lochinvar is clearly stating that even in a P/S setup it should be places as much downstream as possible, to get a realistic temp reading).

I've sent an e-mail to the Lochinvar rep about the min flow rates and max temp rise, plus clarifications on the varspeed pump and that bizzare 0-10V dc input signal ("sys pump in"). Waiting for a response.

For the system pump is simply giving an a BMS the opportunity to see it, control it. But if BMS was controlling the pump then BMS is also controlling the boiler as far was telling it water temp needed. No BMS will take away the boilers firing logic. We do the same thing with Vitodens 200 though I still can't figure for the life of me why I want to give control of my boiler to Amercian logic. Most engineers know nothing about how a mod/con works.

I probably have 100 prints in my office and have yet to see one in 25 years showing the boiler side flow less then the system flow at design. They have fallen into the 20 Degree Rise Trap like everyone else. I do though have a couple that have seen the light after I've redesigned there spec, got it approved and those systems are running and not missing a beat.

Think about a spec. Boiler output is 285,000 need a pump that moves 28gpm. Since when have you seen a buildings heat loss exactly what the boiler puts out and when have you ever seen the primary side influence the secondary side flow rate'? Ok, I got off subject but it's the same in a residential system.

It's not the rise you want to ask, it's what is the minimum flow at low fire so I don't flash to steam.

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

Ok, so the "SYS PUMP IN" 0-10VDC signal would be for the BMS to read a pump that can supply such type of analog output. And that BMS (which can connect to WHN055 in two ways - either through the 0-10V "BMS IN" plug, or via the ModBus module, the latter being like a KMBus from Viessmann hehe).

And based on that reading, the BMS would be able to make other decisions and command the WHN055 modulation rate (it doesn't seem to be a water temp rate, but really a mod rate, according to the service manual - but who knows, as you said about Viessmann never losing it ability to ctrl firing rate, maybe that mod rate is just an input into some other module in the controller, and it's just an 'influence', so basically the controller can still decide the real modulation to proceed with).

Interesting. It's like the Lochinvar's mainboard is trying to fill a "gap" - helping out some BMS systems that are unable to connect to such system pumps directly. So basically, the WHN will convert that analog reading into some digital value in an internal register I guess. I was also intriguing that it was mentioning it only in conjunction with a primary loop / primary flow.

Thanks for the hint - seems logical now. So I shouldn't put too much hope in that interface.

About the question to the rep, ok, let's see first the answer to the most important question - the HX absolute min flow tolerated. Thx.

Chris, about "I probably have 100 prints in my office and have yet to see one in 25 years showing the boiler side flow less then the system flow at design. They have fallen into the 20 Degree Rise Trap like everyone else." -- I'm afraid you were too dense for me, can't understand. Are you trying to suggest that that's the biggest advantage of a P/S hydraulic separation - different flow (and head) needs and the primary/boiler circ should typically had a significantly higher flow than the secondary? But if we aim for higher Delta-T in the boiler (to favour the condensation, due to lower return temp), wouldn't that imply just the opposite? Lower gpm in the boiler (35delta) and higher gpm in the secondary circuit (20 delta)?

f designs and installs. Some think I'm as nuts as Sarah Palin. Ask Loch what they need on the min flow rate side before the boiler will flash to steam. Unlike others my belief and theory based on real life installs here in the US bounced off what is done done across the pond with variable speed pumps is that the boiler flow rate or primary side does not have to match the secondary side.

The goal is to be able to remove the btu/hr created by the heat source to the secondary side. Yes, at times because we zone here it cannot be done but it should be done as to provide the boiler the best opportunity to provide the best overall seasonal efficiency while protecting the source from unwanted wear and tear.

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

what you mean now. The fact that the boiler may wish to "cut corners" and not making good use of those 3 temp sensor :-)

If that's the case, it's still good - it makes the system as a whole more tolerant to mistakes/load mismatches. Especially in directly connected loops. Because at least will be able to sync the pump to the firing rate.

But now, the question is whether the Bumble bee or the alpha would be better? But not being driven by the WHN, how could WHN be in sync with what such type of "independently acting" ECM pumps (especially the Alpha, which doesn't come with temp sensors)?

It's very puzzling: I've always wondered how come those systems across the pond were so tolerant to boiler oversizing or forgiving to piping (and no P/S), even with water tube boilers such as Vaillant, Viessmann or Bosch or Ariston ? That integrated varspeed pump plus the fact that combi units are used in most of the cases, contribute to that. Honestly, when my father or other companies back there were installing these, they have never bothered to do head loss calculations or concerned about min flow rates :-). Heck, they weren't doing even a detailed heat loss calculation. They were just picking up a combi boiler unit appropriate in terms of power to the total square footage of a house or an apartment :-)

And now, I have got so preocupied with formulae and rigurous sizing...Don't get me wrong - it's a good thing, making us aware of how the systems work and getting closer to an ideal "impedance match"/resonance condition.

In other words, the Europe folks tried the one-circuit/one-flow approach and counteracted the "variances" in the system through the use of a var speed pump?

Whereas you think that the "load variance" aspect could be tackled differently, by using the hydraulic separation? Using the "btu 2-conveyer" idea? And even better, by combining the separation also the var speed pump, you would get the best hybrid?

Someone was saying that the hydr. separation somehow came in the market due to the non-condesing boilers, and a need to keep the return temps back into the boiler high enough, to prevent the boiler from condensing/rusting the inner materials?

From an energy transfer perspective, isn't a P/S coupling at disadvantage? I feel that "something" gets lost in this type of connection. In the sense that, instead of transmitting the full thermal energy of the water from the boiler's supply mains into the rads, you deviate part of that back into the boiler.

Wouldn't take longer for the final rads circuit to get the needed BTUs that they would get through a direct connection? I admit I have't studied these aspects too much, but I feel (intuitively) that there are some negatives with the P/S, besides the obvious (impedance matching and separate deltas and flows) advantages.

probably had an integrated bypass inside the boiler. This is quite common and you will find many examples with even a small expansion tank. Euro combi units in particular are expected to be amicable to kitchen or bathroom installations and there is a major incentive to keep things as appliance like as possible.

so basically, we have 220V AC power for the electric stoves and washer/dryers? I now realize that when I have replaced an older electric range by a gas range, the power outlet was something big, with 4 terminals. And had to buy an adapter to connect between 2 "live" terminals, of which one was not in fact a real live but a sort of common mid-tap from a transformer. In order to be able to connect my new gas range to 110VAC.

So, we do seem to have 220V AC here, mono-phase. I have a similar power socket in the furnace room, exactly near the Rinnai tankless. So, using a Magna wouldn't be a problem, would it?

But what about flow requirements for that pump? (besides being kind of pricey :-) )

About those boiler back there, yes indeed, I forgot to mention that they do have an integrated bypass, and the expansion tank is built-in, flat-sized (about 7 liters, what's that, less than 2gallons). And yes, they are mounted in kitchens, bathrooms, hallways or even in balconies/outdoor (but many apartments have the balconies closed, with uPVC windows).

So, if we install a simple bypass here, and a varspeed pump (if driven by boiler), or a Delta-P/T pump without bypass, would that solve all the problems of the Universe ? :-)

For hydraulic separation...Here in North American, It is to protect the less talented from scorching the boiler. Across the pond like Viessmann and many others do, it's to lessen the boiler pump flow rate to allow the system flow rate to take the btu/hr created to the emitters giving the emitter the best opportunity to take those btu/hr out to the space.

We have to dumb down the European technology to fit the installers here in the name of the almighty dollar and our 1950's systems. In all honesty, my rationale comes from the European side and while open to the American side don't take it to the efficiency side.

We try to adapt current technology to 1950's type designed systems instead of taking 1950's designed systems and adapt them to current technology. Look at the frustration you had. A guy can turn a wrench and solder a joint but he couldn't tell you truly how the system works though you could feed you a line of bull..

Please call Loch and find out the min flow rate a low fire and high fire before the boiler will flash the water to steam and ask what that flow rate is based off of..

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

Suppose my hypothesis regarding the variable output signal is correct. Take a look at some documentation for pumps that support 0-10 volt input signals. I might be wrong, but I think the common modulation technique ramps the pump's power (commonly called speed). (There might be other ramp options like delta P, but I can't remember.) This doesn't imply that the flow rate is proportional --this is dependent on the relationship between the pump's characteristic performance curve and the variable voltage signal. Typically there are several options.

Lochinvar wants a pump that is set for linear output. Translation: they want a response to the signal that equates to a nice straight pumping curve with a slope of 1. Normally this is not the case, but these pumps do indeed have an electronically synthesized linear curve as an option. So what's the problem? The assumption here is that the hydraulic resistance is constant. If the hydraulic resistance is variable, the flow will vary independently from the control signal and hence the constant delta T will in fact fluctuate. For example, if you had a TRV based system or zoned manifold system, the hydraulic resistance is independently variable and boiler based constant delta T control cannot be assumed. So essentially, this feature will only work as advertised if the resistance remains constant, or the primary loop is hydraulically separated. This isn't necessarily a bad thing and removing a possibly unstable feedback loop is good, but it definitely makes direct pumping much more tricky if your system revolves around controls that vary the hydraulic resistance. Also, I think it's important to realize that this control scheme, as I mentioned earlier, is more stable (in the sense of boiler hx flow) than a regular fixed delta P pump. A direct pumped regular delta P maintains constant pressure in the face of varying hydraulic resistance, while a regular fixed speed or boiler modulation slaved variable would increase its delta P and not allow flow to slide quite as much.

Regarding the Magna: what's wrong with the Stratos? Isn't that more in your size range? Look up NEMA 6. The circuit needs to be configured for the correct amperage. You shouldn't use an adapter.

is mainly for allowing situations whereas the heating circuit (according to its design conditions) would ask for much higher flow rates than the one tolerated by the boiler/HX ? That is how I understood "Across the pond like Viessmann and many others do, it's to lessen the boiler pump flow rate to allow the system flow rate to take the btu/hr created to the emitters giving the emitter the best opportunity to take those btu/hr out to the space." And with any efficiency-related considerations left aside.

Or, were you maybe implying more - such as, EVEN when the system/heating circuit required flow is still within the boiler's accepted parameters, the P/S config is still beneficial, in the sense that it allows the boiler to work at higher dT and somehow work less (or modulate less)? I admit that it's unclear to me.

Q1: What is the max temp rise (Delta-T) which the boiler can sustain without going into 'alarm' mode.

A1: On Page #65 of the manual under the “Protection Features” the max Delta T is 55F before the boiler reduces the fan speed and if the Delta T reaches 60F the boiler will shut down.

[I have to admit that I missed that paragraph] This is very in sync with what you were saying Chris, about your guy who was deeply involved in the design of another boiler.

Q2: What is the minimum gpm flow rate that Lochinvar wants across the Heat Exchanger - calculated at the minimum firing rate of 11,000 BTU/h and the maximum temp rise supported by the boiler.

A2: Based on the information in the manual the constant speed pumps will maintain 5 gpm but changes with VSP.

[Obviously that's wrong. I re-asked him.]

Q3: What fine-tune parameters are available in the "Smart Control" logic for the customization of the "Const Delta-T" operation which seems to be supported via "0-10V BLR PMP OUT"?

A3: The Knight Smart System controller will always try to maintain a 20F Delta T (Default) but has a range from 15 – 25 using the PC Software.

Q4: In order to use that "0-10V BLR PMP OUT" signal, would a varspeed pump setup be compatible with a direct piping circuit?

A4: Yes you can use a VSP using the “0-10V BLR PMP Out” connection in a system flow application. The outlet sensor looks at the outlet water temp to maintain the proper Delta T (20 gpm as a default) If the Delta T increases the VSP will decrease in speed to maintain proper GPM flow rate.

[That sounds good - it invalidates somehow Eastman's hypothesis - just to be sure I re-asked if the internal sensors will be actually used for that and not just a direct sync with firing rate]

Q5: What is the "0-10V SYS PUMP IN" plug used for?

A5: The “0-10V SYS Pump IN” connection is for a Primary /Secondary system piping arrangement for the VSP system pump so having your VSP system and VSP boiler pumps connection the low voltage board what happens if the system pump decreases in speed so will the boiler pump to prevent the primary loop having a flow rate having a higher flow rate than the secondary piping.

[That's cool - it invalidates the assumption that only an external BMS system can use it - seems to indicate that it's a way for the boiler's logic to sync the flow of the primary (assuming that a VSP is also mounted in the 0-10V BLR OUT) with what happens in the secondary. But still does not say what kind of pump exists for a secondary circuit, which could provide 0-10V output back into the Knight.]

Q6: Can Lochinvar give an example of such smart pump, which can provide an analog 0-10VDC output signal which the WHN055 could then be able to read via "0-10V SYS PUMP IN"?

A6: On page #37 of the manual it gives you 4 different pump manufacturer’s and explains the VSP pump options and setup. VSp pumps are being used more and more in hydronic systems everyday and some of the advantages are reducing Electrical cost, better system boiler / flow relationship and able to better outlet temperature control.

[This seems to be wrong - that page of the manual give only two VS pumps as example, not four: Grundfos UPS26-96FC/VS and Taco 0013 IFC VS. The other 2 examples are for the same pumps, but at 50% ratio. Also those 2 pumps seem to be a classic VFD/Variable Voltage type of pump (non-ECM that is) and ALSO, they do not provide output signals, they only have inputs.]

He has also mentioned that he's having a VSP pump installed in a training room in Burlington, Ontario and he would be happy to show me the setup.

-"This doesn't imply that the flow rate is proportional --this is dependent on the relationship between the pump's characteristic performance curve and the variable voltage signal."

--Correct.

-"Lochinvar wants a pump that is set for linear output. Translation: they want a response to the signal that equates to a nice straight pumping curve with a slope of 1. Normally this is not the case, but these pumps do indeed have an electronically synthesized linear curve as an option."

Some pumps have 2 modes: linear and "proportional weight" or something. The latter I guess reflects the reality better, but since the WHN and maybe other devices across the pond expect linear response, we have to config for linear.

-"So what's the problem? The assumption here is that the hydraulic resistance is constant. If the hydraulic resistance is variable, the flow will vary independently from the control signal and hence the constant delta T will in fact fluctuate. For example, if you had a TRV based system [..] the hydraulic resistance is independently variable and boiler based constant delta T control cannot be assumed. So essentially, this feature will only work as advertised if the resistance remains constant, or the primary loop is hydraulically separated."

--Indeed, sounds logical.

-"Also, I think it's important to realize that this control scheme, as I mentioned earlier, is more stable (in the sense of boiler hx flow) than a regular fixed delta P pump. A direct pumped regular delta P maintains constant pressure in the face of varying hydraulic resistance, while a regular fixed speed or boiler modulation slaved variable would increase its delta P and not allow flow to slide quite as much."

So, if I understand correctly, this boiler-driven type of connection would still be better than a Delta-P "standalone" pump (i.e. not having anything connected to its input, if having such inputs)? But what about a const Delta-T pump such as Taco Viridian or Bumblebee (again working separately)? Would the WHN-driven model still win?

-"Regarding the Magna: what's wrong with the Stratos? Isn't that more in your size range?"

--Well, I wanted the Stratos very much, since the ECO model is 110V. But unfortunately it doesn't seem to support variable voltage interface as attachment. And even if I were to go with their non-ECO model, it would be 230V based and also couldn't find the exact type of interface available for purchasing (only that LONnetwork module was available).

-"Look up NEMA 6. The circuit needs to be configured for the correct amperage. You shouldn't use an adapter. "

--That's right - I must not use an adapter, but plug a Nema6 plug (the one used by high powered stove ranges or laudry dryer). I have checked in the electrical panel - there are two fuses allocated for that circuit. I think I'm ok.

Since my father hasn't left by plane yet (he will fly in this Saturday), I still have time to ask him to buy something rated 230V (50Hz vs 60Hz doesn't matter too much I guess since the ECM variable driver is re-converting to DC anyways?) - I could ask him to buy something from there. Would you have something in mid?

He asked at a store about ECM pumps, and they were mentioning an Italian brand, DAB EVOTRON 40/300 . I'll check into that.

and also their HX seems to be very tolerant. Btw, last evening I looked also through Triangle Tube's manual, and Lochinvar seemed to have inspired from that technology, but they brought in a lot of good stuff in terms of control.

Btw, all WHN's suggesting piping configurations are always showing the boiler pump not pumping away, but mounted close to the return/boiler inlet, and pumping into it.

Now, were you able to undestand something more than me, about the "0-10V SYS Pump IN" ?

happens if the system pump decreases in speed so will the boiler pump to

prevent the primary loop having a flow rate having a higher flow rate

than the secondary piping."

It sounds very much like the SYS PUMP IN signal is used to synchronize flow across a hydraulic separator. I'm not sure if I believe it but that sure sounds like what it does. The boiler probably allows this only when possible, overriding as necessary.

I'm also very surprised there is an additional feedback loop for boiler controlled delta T. The manual really does not read that way, for example, there was no discussion of setting the delta T electronically. I'm wondering if there is another manual for the software that covers this?

They are doing is keeping the primary (boiler) side flow rate matching the system side so there is no mix down stream for the boiler to have to increase it's water temp in order to overcome it. It also eliminates the elevated boiler return temps when the flow of the primary exceeds the secondary.

It's the same thing I've been saying in the Delta-T threads. In those threads I wanted my boiler pump sized for the larger rise and my system for a 20 Delta so the system side could take my boiler side flow rate away from being able to head to the boiler return and elevate my boiler return temps.

Ideally I'd want the type of control the Loch is giving me for my pumps.

"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."

get hung up on imbalanced DT's primary to secondary. If you just concentrate on balancing flows primary to secondary, which is what you want, it just works out that way. Engineers would have trouble wrapping their head around it, because it appears to be a system 'Out of Balance". It's not, and I would argue that it is as close to being in balance as you can make it.